LED Lighting Glossary

A commercial/architectural dimming standard that uses a separate low-voltage signal wire (0-10V) to control brightness. Common in offices, warehouses, and professional installations.

The standard household light bulb shape — a pear-shaped bulb 2.375 inches in diameter, used in most lamps and fixtures.

A slightly larger version of the standard A19 bulb — 2.625 inches in diameter. Used for higher-wattage LED bulbs that need more space for heat dissipation.

Decorative, directional light used to highlight artwork, architectural features, or plants. The third layer of lighting design — adds drama and visual interest.

LED strips where each LED (or small group) can be controlled independently for color and brightness — enabling rainbow effects, animations, and music sync.

The primary, overall illumination in a room — the base layer that provides uniform light for general visibility. Usually from ceiling fixtures, recessed lights, or large floor lamps.

A bayonet cap base with a 22mm diameter, standard in the UK, Australia, and parts of Asia. Push-and-twist to lock into the socket.

A bulge reflector shape 3.75 inches in diameter, designed for recessed can fixtures. Produces a wide, even flood of light directed downward.

A device that regulates current for fluorescent and HID lamps. When upgrading to LED tubes, you may need to bypass the ballast depending on the tube type.

The angle at which light spreads from a bulb. Narrow angles (15-30°) create spotlights; wide angles (60-120°) create flood light.

The manufacturer process of sorting LED chips by color temperature, brightness, and voltage into consistent groups (bins). Tighter binning means more consistent light across multiple bulbs.

A dense array of LED chips bonded directly to a substrate, producing a seamless, dot-free light output. Used in high-end strip lights and downlights.

A 0-100 scale measuring how accurately a light source reveals true colors compared to sunlight. 90+ is considered excellent.

A decorative branched ceiling fixture with multiple light sources. Ranges from traditional crystal designs to modern minimalist styles. Usually the visual focal point of a room.

A bulb with transparent glass that shows the LED filament or chips inside. Produces sharper, more decorative light with visible sparkle.

A measure of light appearance in Kelvin (K) — lower values are warm/yellow, higher values are cool/blue-white. Ranges from candlelight at 2200K to daylight at 6500K.

Designated points on an LED strip where you can safely cut to shorten it. Marked with a scissor icon or copper pads — cutting between marks will damage the circuit.

Always-on front lights that make vehicles more visible during the day. Usually low-intensity LED strips or dedicated bulbs that activate automatically with the engine.

Fixtures designed to minimize light pollution by directing light downward and using warm color temperatures (3000K or below). Certified by the International Dark-Sky Association.

The brightness span a dimmer can achieve — typically expressed as a percentage (e.g., 5%-100%). A wider range means dimming to a lower level without flickering or shutting off.

The standard headlight setting for everyday driving — angled downward and to the side to illuminate the road without blinding oncoming traffic.

A smaller 12mm Edison screw base used in decorative fixtures like chandeliers, wall sconces, and night lights.

The standard Edison screw base used in most household lamps and fixtures. E26 (26mm) is the North American version, E27 (27mm) is the European equivalent.

The efficiency of a light source measured in lumens per watt (lm/W). Higher efficacy means more light for less electricity.

Rapid, repeated changes in light output. Can be visible (strobe effect) or invisible but still cause headaches. Usually caused by incompatible dimmers or poor LED drivers.

A freestanding light fixture that sits on the floor, providing ambient or task lighting without ceiling installation. Types include torchiere (uplight), arc, tripod, and reading lamps.

Low-mounted, wide-beam lights designed to illuminate the road surface in fog, rain, or snow. Positioned below headlights to avoid reflecting off water droplets back at the driver.

A measure of illuminance in imperial units — one lumen per square foot. Commonly used in US building codes and lighting design.

A bulb with a diffused white coating that softens light output, hides internal LED chips, and reduces glare.

A safety device that instantly cuts power when it detects current leaking to ground — preventing electrocution. Required by code for outdoor, bathroom, kitchen, and pool/spa lighting circuits.

A twist-and-lock spotlight base with two pins spaced 10mm apart. Runs on mains voltage (120V/240V) — no transformer needed.

A bi-pin base with two pins spaced 5.3mm apart, used for low-voltage (12V) MR16 spotlight bulbs. Requires a transformer.

A location-based automation trigger that activates lighting actions when your phone enters or leaves a defined area — like turning on porch lights when you arrive home.

A compact single-filament halogen bulb used in headlights and fog lights. Smaller than H7 with a different connector — common in older European and Japanese vehicles.

A dual-filament headlight bulb that handles both low beam and high beam in a single unit. Common in motorcycles, older cars, and many Asian and European vehicles.

A single-filament halogen headlight bulb commonly used for low beam or high beam in European vehicles. One of the most popular bulbs for LED headlight upgrades.

High Intensity Discharge lights that create light by arcing electricity through xenon gas. Brighter and whiter than halogen, but being replaced by LEDs in modern vehicles.

A component (usually aluminum) that absorbs and dissipates heat from LED chips. Critical for lifespan — LEDs don't burn out, they overheat.

The brightest headlight setting with a wider, further-reaching pattern. Used on unlit roads with no oncoming traffic — must be dipped when other vehicles approach.

A safety rating for recessed light fixtures that are approved for direct contact with ceiling insulation. Non-IC fixtures require clearance from insulation to prevent fire risk.

Ingress Protection rating — a two-digit code indicating resistance to dust (first digit, 0-6) and water (second digit, 0-9). Higher numbers mean better protection.

A fixture with LED chips built directly into the housing — no replaceable bulb. Generally more efficient and slimmer, but the entire fixture must be replaced when LEDs fail.

An aluminum housing that mounts LED strips for a professional finish. Includes a diffuser cover that eliminates visible LED dots and improves heat dissipation.

The number of LED chips per meter on a strip light. Higher density produces smoother, more even light with fewer visible dots. Common values: 30, 60, 120, or 144 LEDs/m.

A power supply that regulates current to LEDs, preventing flickering and enabling dimming. Every LED has one — either built into the bulb or as an external unit.

The number of hours until an LED degrades to 70% of its original brightness (L70). Typical LED bulbs are rated 25,000-50,000 hours.

A dimmer type that cuts the leading (front) edge of each AC wave. Originally designed for incandescent and halogen — can cause buzzing and flicker with LEDs.

Lighting systems that operate on 12V or 24V instead of mains voltage (120V/240V). Common in landscape lighting and LED strips — safer to install and requires a transformer.

The unit measuring total visible light output. Unlike watts, lumens tell you how bright a bulb actually is.

A measure of illuminance — how many lumens hit one square meter of surface. Used to specify lighting levels for rooms and workspaces.

A compact multifaceted reflector bulb 2 inches in diameter, commonly used in track lighting, display cases, and landscape fixtures. Usually runs on 12V.

A unified smart home standard backed by Apple, Google, Amazon, and Samsung. Devices certified for Matter work across all major ecosystems — ending the 'which app?' problem.

The lowest wattage a dimmer switch needs to function properly. Many older dimmers require 40-60W minimum — a single 9W LED bulb won't meet that threshold, causing flickering or failure to dim.

The return path for electrical current in a circuit (usually the white wire in US wiring). Many smart switches require a neutral wire — older homes often don't have one in the switch box.

A parabolic aluminized reflector bulb 4.75 inches in diameter. Produces a focused, controlled beam — commonly used for outdoor floods and track lighting.

A dimming method that rapidly switches LEDs on and off thousands of times per second. The ratio of on-time to off-time controls perceived brightness.

A light fixture that hangs from the ceiling by a cord, chain, or rod. Used for both ambient and task lighting — common over kitchen islands, dining tables, and entryways.

A yellow coating applied over a blue LED chip that converts part of the blue light into other wavelengths, creating white light. The phosphor blend determines color temperature and CRI.

A light-sensitive sensor that automatically turns lights on at dusk and off at dawn. Built into some fixtures or available as a standalone add-on for outdoor lighting.

A headlight type that uses a convex lens to focus and shape the light beam into a sharp, defined pattern. Handles LED and HID upgrades much better than reflector housings.

LED technology that combines red, green, and blue diodes to create millions of colors. Variants include RGBW (adds white), RGBWW (adds warm + cool white), and RGBIC (independently addressable segments).

Light fixtures installed flush into the ceiling, creating a clean, unobtrusive look. Also called can lights or downlights. Available as integrated LED or with replaceable bulbs.

A headlight type that uses a chrome-coated bowl to bounce light forward. Simpler and cheaper than projectors, but LED upgrades can cause scattered light and glare issues.

A handheld device for controlling lights without wall switches or apps. Common types include IR (line-of-sight), RF (through walls), and Bluetooth remotes.

A type of LED chip soldered directly onto a circuit board. Common in strip lights — the number (2835, 5050) indicates the chip dimensions in tenths of millimeters.

A central device that bridges smart home protocols (Zigbee, Z-Wave) to your home network. Required for some smart lights, optional for Wi-Fi bulbs.

A saved lighting configuration that sets multiple lights to specific brightness, color, and temperature levels with a single command. Like a preset for your entire room.

A tubular lamp 1 inch (26mm) in diameter, the standard size for commercial fluorescent lighting. LED T8 tubes are direct replacements.

The most common phase-cut dimmer circuit, found in most residential dimmers. Works by chopping the AC waveform. Some TRIAC dimmers work with LEDs, many don't.

Focused, brighter light directed at a specific work area — like a desk lamp, under-cabinet kitchen light, or reading light. The second layer of good lighting design.

A modern IP-based mesh networking protocol for smart home devices. Low-power like Zigbee but uses internet protocol natively — a foundation for Matter.

A wiring configuration that controls one light from two different switch locations — common for hallways, staircases, and rooms with multiple entrances.

A dimmer type that cuts the trailing end of each AC wave cycle. Smooth, quiet, and compatible with most LED bulbs — the recommended type for LED dimming.

A labeling convention that compares an LED bulb's brightness to the incandescent bulb it replaces — e.g., a '60W equivalent' LED produces the same ~800 lumens as a 60W incandescent while using only 9W.

A measure of electrical power consumption. For LEDs, lower wattage delivers the same brightness as higher-wattage incandescent bulbs.

A smart home mesh protocol operating on sub-1GHz frequencies, avoiding Wi-Fi interference. Requires a hub and supports up to 232 devices per network.

A low-power wireless mesh protocol for smart home devices. Requires a hub but is more reliable and scalable than Wi-Fi — each device extends the network for others.